Candling Eggs


In olden times, candling eggs was literally done with a candle. The purpose of candling is to shine a light through the egg so you can see what’s going on inside it. This old-fashioned candle process totally doesn’t work for me. The light just isn’t bright enough. I think I’d need a bonfire.

So I made a candling box.

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How to make a candling box:
1 small cardboard box
a knife
a lightbulb
tea towels

Using a knife, cut a hole–approximately one inch in diameter–into a small cardboard box. Insert the light and cover the top with towels so the only light that escapes is through that small hole. Take the box into a dark room.

Hold the egg to be candled against the hole so that the light is blocked as much as possible except what shines through the egg. After incubating for one week, what you’re hoping to see is a dark spot surrounded by a spiderlike webbing of vessels. This means the embryo is developing correctly.

If it’s not developing correctly, you may see a thin ring, or blood ring, showing that the embryo has died, or a yolk shadow, which means either the embryo has died or the egg was never fertile to begin with. What I believe I’m seeing in my eggs is the yolk shadow.

After my trip to the chicken farm, I managed to screw up fast, within 24 hours, by overheating my eggs with sunlight coming through a window onto the incubator. It’s been seven days since I put these eggs in the incubator and I don’t see any signs of developing embryos in the eggs. I think I’m seeing yolk shadows rather than a blood ring because the eggs really never had a chance to develop at all since they were overheated so soon after incubation began. I’m pretty sure the eggs were fertile.


I’m already incubating a second batch!

And I didn’t throw out the eggs from the first batch yet. Princess found this concept too painful. I won’t keep them around forever because if they are bad, eventually they’ll explode, but I promised her I’d keep them a few more days, at least long enough to candle them again and to candle the second batch after they’ve incubated a week to compare.

Isn’t candling neat? What goes on inside an egg is sorta mysterious and secretive–and uncertain enough to be interesting!

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Posted by Suzanne McMinn on April 9, 2008  

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35 Responses | RSS feed for comments on this post

  1. 4-9

    Good Luck with the eggs…. I have done the same thing, BUT little fingers that live in this house turned up the heater on the fargin incubator – :wall:

  2. 4-9

    I’ve heard of this process, but never knew much about it. Good luck with the new batch. I can’t wait to see the baby chicks.

  3. 4-9

    Wow, what a great website! I am just laughing because we live in an 1890’s house in Lincoln, VA and just last night my husband walked in with blackberry bushes, raspberry bushes and blueberry bushes. AND last night at 9 pm. we were in our sunroom candling our 48 eggs that are about 9 days old…we think they are all duds–but are 100 percent sure since it’s our first time! If these don’t hatch I’m ordering from a hatchery as our kids are SO anxious to start the chicken adventure—and so are we!! the shed is all chicken wired and ready to go! oh and I just had to throw out my farmgirl boots because they were so completely worn out that my toes were coming through :)

  4. 4-9

    Good luck with the second batch of eggs.

    I remember our neighbour in Gaspe, Quebec, used to hatch chickens and pheasants. He had Canada geese too — boy, they were nasty, if you got too close.


  5. 4-9

    Good Luck with the second batch!
    Hopefully they’ll turn out so you will have some chicks.

  6. 4-9

    Good luck! I am waiting anxiously for the arrival of your little flock!

  7. 4-9

    Oh, so cool! Can’t wait to see the results from the next batch!

  8. 4-9

    There sure is a lot more to raising chickens then just buying some eggs. Keep us posted. I hope to have chickens some day.

  9. 4-9

    You farmgirls are so cool. I can’t even imagine doing the candling-chicken-thing. But it’s so much fun to read about it.

  10. 4-9

    Room Remodeling–Day Two.

    Questions I don’t want to hear:

    1) You got a minute so I can show you something?
    2) You ought to consider……

    Tell Steve it’s warm on the coast and flounder season is about to open.

    I promise to never again watch HGTV or
    Flip this Room.

  11. 4-9

    Becki, well, he does love to fish, LOL. (He participates in fishing tournaments.) Good luck!

  12. 4-9

    Well, you’re an amazing woman!

  13. 4-9

    You are wise to keep the eggs ~ Irish Sally just had a terrible mishap with hers, throwing out a whole batch of developing eggs after candling didn’t seem to yield any results.

    Check out her 3/28 entry for more information ~

  14. 4-9

    :biggrin: Sorry about the eggs. Maybe you guys can have a burial for them, and start your own family cemetary at the same time. That’s one of the cool things about farms that I love. I know, it’s kinda morbid, but I’ve always loved cemetaries. The next batch will thrive, I know it!!!!! :flying:

  15. 4-9

    Yes, I’m scared to throw them out! Candling is an imperfect process. I’ve got the batches marked differently so I can tell the eggs apart, and I’ll candle them again later and probably keep them as long as I think it’s safe. When I had ducks, I had a few eggs explode that I’d kept too long when they were bad, so I have to be careful about that, too.

  16. 4-9

    my mom and I use to candle all of our eggs….it truly works. our incubator did not turn the eggs so we took a black magic marker and made a line down one side so the next day we would turn all the eggs over (line side down) and then the next day turn the egg line side up…I totally loved this whole process and looking back I have such fond memories of hatching baby chicks…..another HUGE tip…when it is time for hatching…you will actually hear peeping from inside the egg…so cool…and then they will peck and then you will see little toe nails sticking out and the hardest struggle ever to pull open the egg…DO NOT HELP…it is soo hard to watch this and NOT help them…this is all part of development until the very very very very very last that they are out…they are wet and so tired from the struggle but it is what makes strong healthy chicks…natures way…not our way…Suzanne, listen to me…DO NOT HELP…I must forewarn you…some will make the crack but die in the egg…there was obviously something wrong and it wouldn’t make it anyway…these are the ones you seriously want to assist getting out but it is not meant to be….I remember as a kid being mad at my mom for not doing anything…you will think of me at hatching time!

  17. 4-9

    That reminds me of a pet goose, Emma. She built a nest in the yard around a pvc capped pipe and laid some eggs. They eventually exploded, but she wouldn’t give up on the pvc cap. She sat on that thing so long I thought she was going to die there. I’d go out and feed her and have coffee with her in the mornings. She was one dedicated momma.

  18. 4-9

    I hope they all hatch!

  19. 4-9

    So an ultrasound is the human equivalent of candling? As those eggs tend to be mysterious, secretive and uncertain at times also.

  20. 4-9

    I can’t wait to see when they hatch, how cool for you.

    I won’t be around tomorrow (going away for girls’ weekend at my friend’s gorgeous log house in Galena, IL), but I wanted to wish you A VERY HAPPY BIRTHDAY! I hope you have a wonderful day.

    Peep, I mean peek, in on you next week.


  21. 4-9

    They explode?

    This chicken raising is dangerous business.

  22. 4-9

    Interesting! I always wondered how a person would know if the eggs are going to develop into chickens or not. Cool!

    Good luck with the chickies!

  23. 4-9

    I’m looking forward to the next chick report!

  24. 4-9

    I have done candeling before We were checking for double yolk eggs.
    Good luck with your new batch of eggs!

  25. 4-9

    I’ve never seen a candling box. :eek: Everyone around here does the candling of the eggs with a candle. Good luck with your new batch! :hug:

  26. 4-9

    I have a dozen sitting on my counter that first I let stay in the incubator for a week, now I still can’t throw them out. Maybe tomorrow. Good luck with your new batch. We should be hatching ours on Tuesday.

  27. 4-9

    Can’t wait to see baby chicks :chicken:

  28. 4-16

    I just shared your visit to the chicken farm with my first grade class and they were so excited that I explained candling too. So much fun to see the wide eyes with so many questions. We will watch for the hatching of the eggs. Thank you so much!

  29. 9-16

    How many days now til your hatchday??
    We lost our beloved hens (17) to vicious dogs last weekend, but gathered the 11 eggs left in their nest boxes and have been incubating those for 8 days now. We tried to candle them tonight, but couldn’t see much or very well. The eggs are brown, but we’re still hoping & praying at least some of them are viable & will hatch. If we have to throw these out, it’s going to be a very lonely winter for our family. Sad, lonely & missing our beautiful flock! :cry:

  30. 9-16

    I’m so sorry to hear that! Our chickens were hatched in April.

  31. 4-18

    Way to go on hatching those chicks! I’m so happy for you :) I have a duck egg im incubating, and is due to hatch in a week os so (muscovy) :duck: Do you know if their is a limit to how many times you an candle an egg? I’m candling every other day or so..Anyway Good luck with your new chickies! :eating:

  32. 3-9

    dood if feal bad for you cause that happend to me the first time two but i managed to hatch 12 chicks the second batch now im doin third

  33. 4-29

    Would someone help me I found an egg in the lake near my home and don’t know if it’s still alive or if it’s just unfertile, I’m candling it right now but I don’t see anything should I wait? or you think I should throw it away? :help: Email me at and tell me what I should do I would really appreciate it Thank you.

  34. 4-29

    Kalina Anne, if you found it in a lake, it’s probably not any good at this point!

  35. 4-29

    Aww well it was worth a try.. :cry: It cracked in the warmth anyhow, we have a lot of kids living upstairs and they always scare the ducks away from the nests, or when there trying to snooze..But Thank you anyway. :snoopy:

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